JP3830352B2 - Communication protocol conversion method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention converts a communication protocol between a first communication network using a transaction type transport control protocol (T / TCP) and a second communication network using a normal transport control protocol (TCP). those related to the communication protocol conversion method and equipment for.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a transport control protocol (hereinafter referred to as “normal TCP”) is known as a network protocol used for communication in a communication network. This normal TCP is a protocol having a flow control function used in the transport layer of the network layer, and is used as a standard protocol for communication on the Internet. The normal TCP is also used when a mobile information terminal such as a mobile phone connects to the Internet via a mobile communication network for communication.
[0003]
FIG. 3 shows an example of a sequence of connection establishment processing and connection termination processing when communication is performed between two endpoints (client 501 and server 502) of the communication network using the normal TCP. In this normal TCP, in order to perform reliable data transmission, connection establishment processing and connection termination processing are executed before and after transmission of data to be transferred.
As shown in FIG. 3, in a normal TCP connection establishment process, an initial sequence number (ISN: Initial Sequence Number) of the client 501 and the server are first transferred from the client 501 side that executes active open to the server 502 side that executes passive open. Segment 1 (SYN segment) designating the port number 502 is transmitted. Here, the “segment” is a unit of data when TCP exchanges with a lower network layer. The “SYN segment” is a segment in which “1” is set in a SYN (Synchronize) flag for synchronizing sequence numbers among a plurality of control flags provided in the segment.
Next, after receiving the segment 1, the server 502 responds with the segment 2 (SYN + ACK segment) including the initial sequence number on the server side. Also, in the transmission of segment 2, an acknowledgment is made to the SYN of the client 501 by issuing an ACK obtained by adding 1 to the initial sequence number of the client 501. Next, the client 501 transmits a segment 3 (ACK segment) obtained by adding 1 to the initial sequence number of the server 502 to the SYN of the segment 2 transmitted from the server 502 and confirms the response. In this way, connection establishment processing of a three-way handshake is performed in which three segments are transmitted and received between the client 501 and the server 502. Here, the “ACK segment” is a segment in which “1” is set in an ACK (Acknowledgement) flag that acknowledges the SYN segment or a FIN segment described later.
[0004]
In the normal TCP connection termination process, first, the segment 4 (FIN segment) specifying the sequence number is transmitted from the client 501 side that performs active close to the server 502 side that performs passive close, and the client 501 side The data flow from the server to the server 502 is terminated. Here, the “FIN segment” is a segment in which “1” is set in a FIN (Finish) flag that informs the sender that transmission of data has ended.
Next, when the server 502 receives the segment 4 (FIN segment), the server 502 transmits the segment 5 (ACK segment) obtained by adding 1 to the received sequence number. Then, the server 502 closes the connection and transmits the segment 6 (FIN segment) to the client 501. The client 501 returns a segment 7 (ACK segment) obtained by adding 1 to the received sequence number to the server 502. As described above, in the connection termination process, four segments are transmitted / received between the client 501 and the server 502.
[0005]
[Problems to be solved by the invention]
When the normal TCP is used, a total of seven segments need to be transmitted and received in the connection start process and the connection end process before and after the data flow as shown in FIG. For this reason, when processing a transaction in which the server responds to a request from a client, the overhead of connection establishment processing and connection termination processing occurs, and the transaction processing speed decreases. It was.
In particular, in the case of a mobile communication network such as a cellular phone communication network, it is difficult to ensure a high data transmission speed because a wireless transmission path is interposed, and therefore a transformer capable of performing more efficient transaction processing. Preferably, a port layer protocol is used.
[0006]
Therefore, in order to provide a transport layer capable of avoiding the overhead of the connection establishment process and the connection termination process and performing an efficient transaction process, a transaction-type transport control protocol (hereinafter referred to as “T / TCP”). ")"). This T / TCP is a protocol whose definition is described in RFC (Request For Comment) 1379 and 1644, and the last value of the connection count (hereinafter referred to as “CC”) received from each client is stored in the server. By doing so, connection establishment processing of the three-way handshake is avoided, and efficient transaction processing is achieved.
[0007]
However, in the Internet world, the aforementioned normal TCP is still widely used. Therefore, if the T / TCP is used for the first communication network including the poor quality transmission line such as the mobile communication network, the first communication network and the second on the Internet side using the normal TCP are used. It is necessary to convert the communication protocol to transfer data with other communication networks. The communication protocol conversion involves a problem of performing data transfer by converting the protocol at high speed without being restricted by the connection establishment process of the three-way handshake in the normal TCP.
[0008]
The present invention has been made under the above background, and its object is to provide data accompanying communication protocol conversion between a first communication network using T / TCP and a second communication network using normal TCP. the transfer is to provide a communication protocol conversion method and equipment it is possible to perform a high speed.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 includes a first communication network using a transaction type transport control protocol (T / TCP) and a second communication network using a normal transport control protocol (TCP). A communication protocol conversion method for converting a communication protocol with a communication network using a communication protocol conversion device , wherein when a SYN segment including data to be transferred is received from the first communication network, the first communication network The T / TCP is transmitted between the communication protocol converter and the first communication network by transmitting a SYN + ACK segment to the first communication network and receiving an ACK segment responding to the SYN + ACK segment from the first communication network. The transmission target data is transmitted / received by the first communication network, and includes the transfer target data from the first communication network. After receiving the YN segment and before receiving the ACK segment in response to the SYN + ACK segment from the first communication network, a connection establishment process between the communication protocol converter and the second communication network is performed. It is characterized by starting .
According to a second aspect of the present invention, in the communication protocol conversion method according to the first aspect, a connection establishment process with the second communication network is started before the SYN + ACK segment is transmitted to the first communication network. It is characterized by that.
According to a third aspect of the present invention, in the communication protocol conversion method according to the first or second aspect, the communication protocol conversion device, after completing the connection establishment process with the second communication network, The transfer target data received from one communication network is transmitted to the second communication network.
According to a fourth aspect of the present invention, in the communication protocol conversion method according to any one of the first to third aspects, the transfer target is received when the SYN segment including the transfer target data is received from the first communication network. Data is stored, and after the connection establishment process with the second communication network is completed, the stored transfer target data is transmitted to the second communication network. Is.
The “SYN + ACK segment” is a segment in which “1” is set in both the SYN flag and the ACK flag.
In the communication protocol conversion method according to claims 1 to 4, when the first SYN segment including the transfer target data is received from the first communication network, the SYN + ACK segment is transmitted to the first communication network, and the first communication is performed. By receiving an ACK segment in response to the SYN + ACK segment from the network, transmission / reception processing of data to be transferred by T / TCP is performed between the communication protocol converter and the first communication network. Then, prior to receiving an ACK segment in response from the first communication network even after having received a SYN segment containing data to be transferred from the first communication network to SYN + ACK segment, the communication protocol converter and the second A connection establishment process with the communication network has started. In this way, while performing segment transmission / reception for the first data transfer process between the communication protocol conversion apparatus and the first communication network, unnecessary communication between the communication protocol conversion apparatus and the second communication network is eliminated. By starting the connection establishment process between the two, it is possible to obtain a response quickly from the second communication network.
[0010]
According to the invention of claim 5 , communication is performed between a first communication network using a transaction type transport control protocol (T / TCP) and a second communication network using a normal transport control protocol (TCP). A communication protocol conversion device for converting a protocol, a first data transmission / reception unit that transmits / receives data to / from a first communication network, and a second data transmission / reception unit that transmits / receives data to / from a second communication network with the door, said first data transceiver, when receiving a SYN segment containing data to be transferred from the first communication network, sends a SYN + ACK segment to the first communication network, the first By receiving an ACK segment in response to the SYN + ACK segment from the communication network of the communication protocol conversion device and the first communication network, When the SYN data including the transfer target data is received from the first communication network, the SYN + ACK segment is transmitted to the first communication network. By receiving an ACK segment in response to the SYN + ACK segment from the first communication network, transmission / reception processing of the data to be transferred by the T / TCP between the communication protocol converter and the first communication network The second data transmitting / receiving unit receives an ACK segment responding to the SYN + ACK segment from the first communication network after receiving the SYN segment including the transfer target data from the first communication network. Before receiving, start a connection establishment process between the communication protocol converter and the second communication network That, it is characterized in.
According to a sixth aspect of the present invention, in the communication protocol conversion device according to the fifth aspect, the second data transmitting / receiving unit transmits the SYN + ACK segment to the first communication network before transmitting the second communication network. The process of establishing a connection with the server is started.
The invention according to claim 7 is the communication protocol converter according to claim 5 or claim 6, wherein the second data transmitting / receiving unit completes connection establishment processing with the second communication network, The transfer target data received from the first communication network is transmitted to the second communication network.
The invention according to claim 8 is the communication protocol conversion apparatus according to claim 7, further comprising a data storage unit that stores the transfer target data received by the first data transmitting / receiving unit, wherein the second data transmitting / receiving unit includes: After completing the connection establishment process with the second communication network, the transfer target data stored in the data storage unit is transmitted to the second communication network. It is.
9. The communication protocol conversion device according to claim 5, wherein when the first data transmitting / receiving unit receives the first SYN segment including the transfer target data from the first communication network , the first data transmission / reception unit transmits a SYN + ACK segment to the first communication network. By transmitting and receiving an ACK segment in response to the SYN + ACK segment from the first communication network, transmission / reception processing of data to be transferred by T / TCP is performed between the communication protocol converter and the first communication network. The second data transmitting / receiving unit receives the SYN segment including the transfer target data and before receiving the ACK segment responding to the SYN + ACK segment transmitted to the first communication network from the first communication network. The process for establishing a connection with the second communication network is started. In this way, while performing segment transmission / reception for the first data transfer process between the communication protocol conversion apparatus and the first communication network, unnecessary communication between the communication protocol conversion apparatus and the second communication network is eliminated. By starting the connection establishment process between the two, it is possible to obtain a response quickly from the second communication network.
[0011]
Particularly, in the communication protocol conversion method according to claim 4 and the communication protocol conversion device according to claim 8, when the first SYN segment including the transfer target data is received from the first communication network, the received transfer target data is stored in the data storage unit. Once stored, prepare for data transmission to the second communication network. Then, after the connection establishment between the communication protocol conversion device and the second communication network is completed, the segment including the transfer target data stored in the data storage unit is transmitted to the second communication network. .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention is used between a cellular phone communication network as a first communication network and a communication network (hereinafter referred to as “Internet side communication network”) connected to the Internet as a second communication network. A communication protocol conversion method and apparatus for performing data transfer and an embodiment applied to a data communication system will be described.
FIG. 2 is a block diagram of a data communication system including the communication protocol conversion apparatus according to the present embodiment. This data communication system includes a mobile phone communication network 10, a communication protocol conversion device 20, and an Internet side communication network 30.
[0014]
The mobile phone communication network 10 includes a plurality of base stations 13 that transmit / receive data to / from a mobile phone 11 as a mobile information terminal via a wireless communication line 12, and an exchange 14 that switches data transmission / reception with respect to each base station 13. And. In this cellular phone communication network 10, a transaction-type transport control protocol T is used as a transport layer communication protocol so that high-speed data transfer is possible even when a wireless communication line having a relatively low transmission rate is included. / TCP is used. Unlike normal TCP, this T / TCP does not require a three-way handshake connection establishment process prior to data transmission, and can transfer data at a higher speed than when using normal TCP. Become. This is particularly advantageous when performing transaction processing in which a server responds to a request from a client (mobile phone).
[0015]
The communication protocol converter 20 includes a first data transmitter / receiver 21 that transmits / receives data to / from the mobile phone communication network 10, a second data transmitter / receiver 22 that transmits / receives data to / from the Internet-side communication network 30, And a data processing unit 23 that performs data processing including communication protocol conversion described later.
The first data transmission / reception unit 21 and the second data transmission / reception unit 22 perform signal processing in the lowest link layer (also referred to as “network interface layer”) in the network protocol layer. Handles the hardware aspects of the physical interface.
The data processing unit 23 includes a data storage unit 23a, a segment generation unit 23b, and a timing control unit 23c, and includes a CPU, a RAM, a ROM, and the like. The data storage unit 23 a temporarily stores data received from the mobile phone communication network 10 and the Internet side communication network 30. In addition, the segment generation unit 23 b generates each segment to be sent to the mobile phone communication network 10 and the Internet side communication network 30. In addition, the timing control unit 23 c controls the transmission timing of each segment transmitted toward the mobile phone communication network 10 and the Internet side communication network 30. The data processing unit 23 including these performs data processing such as packet processing using IP (Internet Protocol) in addition to communication protocol conversion in the transport layer described later.
[0016]
The Internet-side communication network 30 includes a gateway server 31 for connecting to the Internet 40. In the Internet-side communication network 30, normal TCP widely used in the Internet 40 is adopted as a transport layer communication protocol. The gateway server 31 and the communication protocol converter 20 are connected by a wired communication line 32. The wired communication line 32 is configured by a line with a limited transmission data capacity such as a short mail, if necessary, or transmits a relatively large amount of data such as a long mail or image data of about 3000 characters. It can be configured with a broadband line that can be used, or it can be configured such that a plurality of these lines can be switched and used.
[0017]
FIG. 1 shows transmission / reception of segments when data is transmitted from a mobile phone 11 in a mobile phone communication network 10 to a WWW (World Wide Web) server at a specific site on the Internet 40 connected to the Internet-side communication network 30. FIG.
In data transmission / reception with the mobile phone communication network 10 in the data processing unit 23 of the communication protocol conversion device 20, first, the SYN segment (segment 101) including the transfer target data (data1) is transmitted via the first data transmission / reception unit 21. Receive from the mobile phone communication network 10. In this segment 101, the FIN flag for notifying the end of data transmission and “1” are both set. Further, the segment 101 is provided with “CC” for setting a 6-bit connection count value, which is an option specific to T / TCP. The data processing unit 23 compares the value (= x) in the CC in the segment 101 with the last CC value in the previous connection cached in the data processing unit 23, and the value in the CC (= x ) Is larger than the cached CC value, it is determined that the transfer target data included in the segment 101 is new data, and is transferred to the Internet side communication network 30. On the other hand, when the received CC value (= x) is smaller than the cached CC value, or when the CC value is not cached in the data processing unit 23, the normal three-way handshake in TCP is performed. Executed.
[0018]
Next, the data processing unit 23 that has received the segment 101 from the mobile phone communication network 10 transmits a segment 102 (SYN + ACK segment) to the mobile phone 11. In this segment 102, “1” is set in the ACK flag for confirming and responding to the SYN in the segment 101 together with the SYN flag. Further, this segment 102 has a data area “CC” for setting the CC value on the transmission side, and a predetermined value (= y) for the communication protocol converter 20 is set in this “CC”. ing. Furthermore, it has a data area “CC.ECHO” for echoing the received CC value, and the CC value (= x) of the segment 101 is set in this “CC.ECHO”.
[0019]
Next, when the segment 103 (ACK segment) for confirming the response to the SYN is transmitted from the mobile phone 10 that has received the segment 102, the communication protocol converter 20 transmits the segment 103 transmitted from the mobile phone 10. Receive. Thereby, the transfer of one data from the mobile phone 11 to the communication protocol converter 20 is completed.
As described above, data transmission from the mobile phone 1 of the mobile phone communication network 10 to the communication protocol converter 20 is completed by transmission / reception of the three segments 101, 102, and 103.
[0020]
On the other hand, in the data transmission / reception with the Internet side communication network 30 in the data processing unit 23 of the communication protocol conversion device 20, first, after receiving the segment 101 from the mobile phone communication network 10, the segment 102 is transmitted to the mobile phone communication network 10. Prior to this, connection establishment processing for a WWW server at a specific site of the Internet side communication network 30 is started via the second data transmitting / receiving unit 22. The connection establishment process is started by transmitting a SYN segment (segment 201) to the Internet side communication network 30. Subsequent segment transmission / reception is performed by the normal TCP procedure shown in FIG. 3, and after the data transfer is completed, connection termination processing is performed by the normal TCP procedure shown in FIG.
[0021]
Here, when a plurality of transfer target data (data1, data2, data3,...) Are continuously transferred from the mobile phone 11 to a WWW server at a specific site on the Internet 40, the segments 101 to 101 are transmitted from the mobile phone communication network 10. While performing transmission / reception of 103 and receiving transfer target data, after performing connection establishment processing to the Internet-side communication network 20, the segment including the transfer target data is repeatedly transmitted, and finally connection termination processing is performed. To do.
[0022]
As described above, according to the present embodiment, unnecessary segment transmission / reception is omitted from the transmission of the segment 101 to the reception of the segment 102 with respect to the first data transfer process with the mobile phone communication network 10. The connection establishment process for can be started. Therefore, as compared with the case of a conventional communication protocol conversion method which has initiated a connection establishment process for the Internet communication network 30 after the reception of the segment 101 to 103 is completed, obtaining a second communication network or al early response Therefore, it is possible to increase the speed of data transfer accompanied by communication protocol conversion.
[0023]
In the above embodiment, after the segment 101 (SYN segment) is received from the mobile phone communication network 10 and before the segment 102 (SYN + ACK segment) is transmitted to the mobile phone communication network 10, the Internet side communication network 30 is specified. The connection establishment process for the site WWW server is started, but the connection to the Internet side communication network 30 after the segment 102 is transmitted and before the segment 103 (ACK segment) is received from the cellular phone communication network 10. The establishment process may be started.
[0024]
In the above embodiment, a case has been described in which the first communication network using T / TCP is a mobile phone communication network including a wireless communication line that performs direct communication between the mobile phone 11 and the base station 13. The present invention can also be applied to a case where the first communication network using T / TCP is a communication network including a satellite communication line for performing communication between a mobile phone on the ground or a base station and a communication satellite. is there.
In the above embodiment, the case where the second communication network using normal TCP is a communication network (Internet side communication network 30) including a communication line for connecting to the Internet (The Internet) has been described. The present invention can also be applied to a case where the second communication network using normal TCP is a communication network not intended for connection to the Internet.
As described above, the present invention can be used in each communication network as long as the communication protocol is converted between the first communication network using T / TCP and the second communication network using normal TCP. The present invention can be applied without being limited to the type of communication line or the purpose of the communication network.
[0025]
【The invention's effect】
According to the first to eighth aspects of the present invention, while performing segment transmission / reception for the first data transfer processing between the communication protocol conversion device and the first communication network, unnecessary protocol transmission / reception is omitted and communication protocol conversion is performed. By starting the connection establishment process between the device and the second communication network , a response can be obtained quickly from the second communication network, so that it is possible to speed up data transfer with communication protocol conversion. There is an excellent effect of becoming.
[Brief description of the drawings]
FIG. 1 is a sequence diagram showing segment transmission / reception in data transfer with communication protocol conversion according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a schematic configuration of a data communication system including a communication protocol conversion apparatus that performs data transfer accompanied by the communication protocol conversion.
FIG. 3 is a sequence diagram showing segment transmission / reception in connection establishment processing and connection termination processing using normal TCP.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Mobile phone communication network 11 Mobile phone 12 Wireless communication line 13 Base station 14 Switch 20 Communication protocol converter 21 First data transmission / reception unit 22 Second data transmission / reception unit 23 Data processing unit 23a Data storage unit 23b Segment generation unit 23c Timing Control unit 30 Internet side communication network 31 Gateway server 32 Wired communication line 40 Internet

Claims (8)

A communication protocol is converted between a first communication network using a transaction type transport control protocol (T / TCP) and a second communication network using a normal transport control protocol (TCP) by a communication protocol converter. A communication protocol conversion method for converting,
When a SYN segment including data to be transferred is received from the first communication network, a SYN + ACK segment is transmitted to the first communication network, and an ACK segment responding to the SYN + ACK segment is transmitted from the first communication network. By receiving, the transmission / reception processing of the transfer target data by the T / TCP is performed between the communication protocol converter and the first communication network,
After receiving the SYN segment including the transfer target data from the first communication network and before receiving the ACK segment responding to the SYN + ACK segment from the first communication network, the communication protocol converter and the A communication protocol conversion method characterized by starting a connection establishment process with a second communication network .   The communication protocol conversion method according to claim 1,
  Before transmitting the SYN + ACK segment to the first communication network, a communication protocol conversion method characterized by starting a connection establishment process with the second communication network.   In the communication protocol conversion method according to claim 1 or 2,
  After the connection establishment process with the second communication network is completed, the transfer target data received from the first communication network is transmitted to the second communication network. Communication protocol conversion method.   In the communication protocol conversion method according to any one of claims 1 to 3,
  When the SYN segment including the transfer target data is received from the first communication network, the transfer target data is stored, and after the connection establishment process with the second communication network is completed, the storage is performed. A communication protocol conversion method characterized by transmitting the transferred data to be transferred to the second communication network. Communication protocol conversion for converting a communication protocol between a first communication network using a transaction type transport control protocol (T / TCP) and a second communication network using a normal transport control protocol (TCP) A device,
A first data transmitter / receiver for transmitting / receiving data to / from the first communication network;
And a second data transceiver which transmits and receives data to the second communication network,
The first data transmission / reception unit includes:
When a SYN segment including data to be transferred is received from the first communication network, a SYN + ACK segment is transmitted to the first communication network, and an ACK segment responding to the SYN + ACK segment is transmitted from the first communication network. By receiving, the transmission / reception processing of the transfer target data by the T / TCP is performed between the communication protocol converter and the first communication network,
The second data transmitter / receiver
After receiving the SYN segment including the transfer target data from the first communication network and before receiving the ACK segment responding to the SYN + ACK segment from the first communication network, the communication protocol converter and the Start a connection establishment process with the second communication network;
A communication protocol converter characterized by that.   In the communication protocol converter according to claim 5,
  The second data transmitting / receiving unit starts a connection establishment process with the second communication network before transmitting the SYN + ACK segment to the first communication network. apparatus.   In the communication protocol converter according to claim 5 or 6,
  The second data transmitting / receiving unit, after completing the connection establishment process with the second communication network, transmits the transfer target data received from the first communication network to the second communication network. A communication protocol converter characterized by the above.   The communication protocol converter according to claim 7, wherein
  A data storage unit for storing the transfer target data received by the first data transmitting / receiving unit;
  The second data transmitting / receiving unit, after completing the connection establishment process with the second communication network, transfers the transfer target data stored in the data storage unit to the second communication network. A communication protocol converter characterized by transmitting.

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